Microplastics originated from Plasmix-based materials caused biochemical and behavioral adverse effects on Daphnia magna

The implementation of advanced recycling techniques represents a key strategy for mitigating the mismanagement and the environmental impact of plastic waste. A limited array of plastic polymers can be efficiently recycled, while a notable portion of plastic waste remains unrecyclable. In Italy, this residual, heterogeneous fraction is referred to as Plasmix. Because of its complexity and non-homogeneous composition, Plasmix is primarily directed towards low-value applications. However, recent developments in laboratory-scale mechanical recycling have enabled the creation of new plastic materials from Plasmix. Prior to their application, these materials must undergo rigorous eco-safety evaluation. The present study aims to assess the potential toxicity of microplastics (MPs) from Plasmix-based materials on the freshwater crustacean Daphnia magna. Specifically, this study investigated sub-individual and individual effects induced by a 21-day exposure to different concentrations of MPs generated from the grinding of naïve and Additivated Plasmix-based materials (hereafter referred to as Px-MPs and APx-MPs, respectively). Sub-individual endpoints focused on changes in oxidative status, including the modulation of antioxidant and detoxifying enzyme activities, as well as oxidative damage, such as lipid peroxidation. Individual level endpoints included alterations in survival and reproduction. Microscopy analyses confirmed the ingestion of both Px-MPs and APx-MPs by D. magna individuals. An oxidative stress condition raised in organisms exposed to Px-MPs, whereas no effect was observed in individuals exposed to APx-MPs. Although survival was not affected, a significant impairment in reproductive output was detected at the end of exposure to all the concentrations of both MP types. These findings suggest that even low concentrations of Px-MPs and APx-MPs could negatively affect the health status of D. magna, underscoring the need for further research to complete the risk assessment of Plasmix-based materials prior to their use in consumer products.